Although the application of steam, as a motive power to the car riages running upon railways, has been of a comparatively-speaking recent introduction, the efforts of mechanicians had long been turned towards that object. Watt, Symington, Trevithiek, Blenkinsop, Chap man, Brunton, and others, had striven for more than forty years to discover the means of propelling carriages by steam upon common turnpike roads, or upon railways ; but after numerous failures, the whole class of machine-makers seem, about the year 1812, to have arrived at the conviction that a simple band wheel could not exercise a sufficient amount of friction upon a road surface to cause the carriage to advance. For many years the efforts of steam-carriage builders were directed to obviating this imaginary difficulty, and rechet wheels, jointed levers, mechanical legs of every shape and form, were intro duced, to the detriment of the roadway, and to the diminution of the useful power of the engine. About 1814, however, George Stephenson constructed for the Killingworth Colliery, Durham, a steam-engine, bearing two cylinders seated upon a boiler mounted on wheels, and immediately above the axles of those wheels, which bore cranks con nected with the piston heads of the cylinders, and were made to revolve in unison by means of vaucanson chains working over barrels on the respective axles. The engines made upon Stephenson'e prin ciples were not at first much esteemed, and it was long before they became of general use ; but gradually they were adopted in the colliery districts; and about the year 1826, Stephenson even applied one of them for passenger traffic on the Stockton and Darlington line. The velocity attained by these engines was not more than about nice miles an hour, when used for passenger traffic ; or than five miles per hour for goods.
One of the great inconveniences felt in the early days of the use of the locomotive, arose from the number and the insecurity of the joints of the rails when the cast-iron fish-bellied ones were employed, and from tho brittle nature of the iron itself. The discovery by Mr. Birkenshaw of a mode of efficiently and cheaply rolling malleable iron rails, which was patented by him In 1820, constituted, therefore, a most important link in the chain of mechanical invention, by whose means the railway system has been perfected. The fibrous character of the wrought-iron makes it far less likely to break under concussions than cast-iron would be ' • and the sectional form generally given to the H or double-headed rail, offers a very great resistance to defiec tion. It is remarkable that rails which are constantly travelled over do not rust; but it is important that they should be made of a metal as crystalline as it possibly can be, consistently with the retention of its malleability; soft, fibrous iron is, in fact, not suited for the manu facture of rails. Wrought-iron rails are made about 15 or 21 feet in length, instead of 3 or 4 feet, as in the case of the cast-iron rails.
When the projectors of the Liverpool and Manchester Railway were engaged in the design and execution of that great work in the year 1825, and the following years, the capabilities of the locomotive engine were still so little known that it was for a long time a matter of dis cussion whether or not that description of motive power should be adopted. The directors were soon convinced that horsepower would
not enable them to attain the speed they considered necessary ; but the result of the experiment upon the Stockton and Darlington line had not been sufficiently decisive to induce them at once to try the new locomotives. They therefore consulted some of the most eminent engineers of the day, and after easefully examining the reports of Messrs. Rastriek and Walker in favour of fixed engines, and those of Messrs. Stephenson and Locke in favour of locomotives, the directors wisely determined to use locomotives, and to offer a premium for the best engine of that description which should fulfil certain conditions. The history of this competition is so well known that it would be useless to repeat it here ; and it may suffice to observe that tbe pre mium! was won by Messrs. Stephenson and Booth, who produced the Racket engine, of which an illustration is given (fig. 8) ; and thus Inaugurated the most important revolution in the means of material civilisation which any age has witnessed. [Sreeussesox, GEORGE, in Thee. Div.] The French mining interest had not neglected to avail themselves of the advantage offered by the edge rails in diminishing the cost of their heavy traffic ; and they had constructed about 1826, the railways from Roanne to St. Etienne, and from St. Etienne to Lyon and tc Andrezieux. M.:Sequin, the engineer of one of these linee, had also constructed some locomotive engines for the purpose of drawing the wagons; and in them he first introduced the use of small tuber paling from the fire-box to the chimney. Messrs. Stephenson and Bury adopted this plan in constructing the boiler of the Rocket, and thin increased in a notable mariner the evaporating power of their engine; and they increased the draught by causing the waste steam to escape by the funnel. The cylinders of the Rocket were fixed externally ; a system to which after many trials some engine-makers seem disposed to return ; and the early locomotives invariably were heated by coke, ['he Rocket had four wheels, not coupled, and its weight was only 4 ;ens 5 cwt. ; it attained with a gross load of 17 tons, an average speed )f 14 miles, and in some instances it attained a speed of 17 miles [ser hour. It is curious to contrast these figures with the ones ,onnected with the more recent locomotives. Thus, the weight of some of the passenger engines on the North Western line (without their guppies of coke and water) is not less than 27 tons ; the weight of some of those on the Great Western line is not less than 31 tons ; and some of the engines used on the Scemering line are even of 48 tons weight and have six coupled wheels. The various considera tions connected with the weight and the dimensions of locomotives belong however to the records of the subsequent history of the railway system ; its general (or perhaps rather its preliminary) history was closed by the triumphant success of the Rocket.